


Open Up

by nihilistshiro



Category: Voltron: Legendary Defender
Genre: Alpha Shiro (Voltron), Alpha/Omega, Alternate Universe - Modern Setting, Anal Fingering, Double Penetration, Knotting, M/M, Mating Cycles/In Heat, Non-traditional biology, Omega Keith (Voltron), Oral Sex, Other, Sex Toys
Language: English
Status: Completed
Published: 2019-11-24
Updated: 2019-11-24
Packaged: 2021-02-26 07:08:03
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,653
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21539509
Author URL: https://archiveofourown.org/users/nihilistshiro/pseuds/nihilistshiro
Summary: Shiro comes home to find Keith mid-heat and is gracious enough to help him out.
Relationships: Keith/Shiro (Voltron)
Comments: 6
Kudos: 219





	Open Up

**Author's Note:**

> Helloooo!!
> 
> This one-shot is based on a Twitter thread featuring Sheith as cops and in an a/b/o setting. You can read that thread [here.](https://twitter.com/NihilistShiro/status/1197658140772204544?s=20)
> 
> Also - just note that Keith's omega biology includes an additional 'entrance' bc this is my damn fic and I wanted it that way. 
> 
> Annnyyy who, I hope you enjoy it!

Shiro took off his jacket and hung it on the coat rack, closing the door to his apartment and sliding the lock into place.

He’d requested a week off work to be with Keith during his heat, and his last shift was over. Keith’s scent already permeated the apartment—the spicy, cinnamon and cherry smell Keith usually gave off morphing into a hypnotic musk, his omega body pumping out pheromones, calling to his alpha.

Shiro swallowed thickly, the hair on his arms lifting, his nostrils flaring to pull more of the delicious scent in.

He toed off his shoes and tugged his tie loose, walking further into the apartment, his firearms still hanging from the leather holster strapped around his broad frame. The closer he got to the bedroom, the heavier scent was, and it wrapped around Shiro like a swath of the finest silk, sliding across his skin and lighting a fire in his blood.

He rubbed the cold, metal fingers of his prosthetic along the teeth marks slashed across his wrist, and the sensation sent a shudder through him, the gland already leaking potent oil. He opened the door to the bedroom and froze.

Keith lay strewn across a messy nest—Shiro’s shirts, pants, and underwear piled high on the king-sized bed, most of which was dirty, pulled from the hamper. Keith’s skin glistened, covered in a thin sheen of sweat, cum still drying on his stomach. There were a handful of toys lying around him, used and discarded. 

“Keith,” Shiro whispered, his eyes dilating, pulse hammering in his ears.

Keith’s violet eyes cracked open, and he looked up at Shiro through his lashes, his dark hair damp with sweat. Shiro walked over to him, pushing the fringe back off his forehead. Keith leaned into the touch and hummed contentedly.

Keith whined, his hand reaching for Shiro’s wrist and pulling it down to his neck so he could rub their glands together. His greedy mouth slurped up the oil dribbling from Shiro’s gland, his sharp teeth sinking into the mate mark, breaking the skin.

“Shit,” Shiro groaned, his eyes rolling back as Keith lapped up the droplets of crimson, a few sprinkling the nest and adding to the intoxicating, fragrant fog that filled the room.

When Keith finished, he released Shiro, dropping back onto the pillows and clothes, wiping his mouth with the back of his hand. Shiro quickly ditched his holster, setting the firearms on the dresser before he stripped away his clothes.

Keith watched him, his hand lazily stroking his semi-hard cock, legs falling open to expose the red marks on his inner thighs. His lips were sticky with slick, and Shiro wanted nothing more than to bury his face between Keith’s legs and clean him.

And so that’s what he did.

Shiro crawled into the nest, his heavy palms resting on top of Keith’s glands, fingers digging into his thighs as he ran his tongue along Keith’s cock and moved lower, past his balls, to his front entrance. 

Keith’s fingers dove into Shiro’s hair, tugging hard as his hips bucked beneath Shiro’s clever tongue. His slick was sweet and nacreous, and Shiro moaned as it flooded his senses. Keith’s cock bobbed, and Shiro reached up to circle it with his left hand, stroking him as he devoured Keith’s front. 

Keith yanked at Shiro’s hair, a whimper escaping him. His muscles were tensing, and he clawed at Shiro’s back and shoulders, writhing beneath his touch. Shiro drew his mouth back, replacing it with two metal fingers that teased and probed Keith’s entrance. 

“Kashi, please. I need, _hhnnnggg—ahhhhh!_ Please! Need your knot!”

Shiro slid his fingers in deeper, Keith slicking anew as Shiro worked him open. He was already loose from the toys, but he needed his alpha’s knot in a way no amount of silicone could replace. 

Shiro kissed the tip of Keith’s cock and slipped his fingers out, collecting as much slick as he could before moving them lower to Keith’s ass. 

“Fuck!” Keith cried out as Shiro pressed one glistening digit past the tight ring of muscle. 

Shiro bobbed up and down, lips pursing around Keith’s cock as he added a second finger, scissoring them as he stretched Keith’s rim. 

“You’ve been busy,” Shiro said as he moved off of Keith and sat back on his heels, watching his fingers fuck in and out of Keith’s ass.

The way Keith was panting, his hands gripping at the random assortment of fabric around him, his pale skin flushed and trembling—it all made Shiro mad with lust, red hazing over his vision as his mind narrowed to a single focal point.

“That’s it, baby,” Shiro cooed. “Open that ass for me.”

Keith keened, knees falling wider as he tried to tilt his pelvis up to afford Shiro better access.

“Such a good little mate,” Shiro said, retracting his fingers and reaching for one of the large, knotted dildos. “Let me see you take this in your ass, baby.”

Keith cried out as Shiro sank the dildo past the tight ring of muscle, pushing it in and out, his own cock achingly hard as he tormented Keith with his ministrations. 

“That’s a good boy. Take it. More. Take more, baby.”

Keith was gasping for breath by the time Shiro finally sank in the dildo’s fat knot. He licked his lips, savoring the sight of his omega spread wide and wanting. 

“You still want my knot, baby?”

“Yes!” Keith’s honey voice was wrecked, and it was music to Shiro’s ears.

“Tell me.”

“I want your knot, Kashi. _Please!_ Please knot me.”

Shiro’s grin was voracious as he crawled up Keith’s body, kneeling on either side of his head, one fist wrapped around his cock as it nudged the seam of Keith’s lips.

“Open up, baby. Suck on me.”

Keith’s mouth popped open eagerly, and he grabbed Shiro’s haunches, swallowing him whole. He moved like it was his duty in life to blow his alpha, saliva pooling at the corners of his mouth. Shiro steadied himself with one hand on the wall, his hips thrusting forward as Keith swirled his tongue around the shaft, one hand reaching between them to gently tickle Shiro’s balls.

Keith gagged around Shiro’s cock, and Shiro pulled back, leaning down for a sloppy kiss. Tasting himself on Keith’s lips made his cock jump, and he couldn’t wait any longer. He shifted, grabbing his cock and lining it up with Keith’s front. 

He slid his cock through Keith’s slick before pressing in. He could feel the dildo in Keith’s ass, and he growled, slamming his hips forward in one brutal thrust. Keith sobbed, his nails dragging down Shiro’s chest.

“So tight,” Shiro grunted, pulling out slightly before snapping his hips forward. 

He grabbed Keith’s knees, hoisting his legs up, so his ankles rested on Shiro’s shoulders. One arm wrapped around Keith’s thighs, and Shiro began a savage pace, each thrust prodding the dildo in Keith’s ass.

Keith was already overstimulated, the nest covered with his cum and sweat. Shiro pressed forward, folding Keith in half as he fucked into him.

“Grab your ankles,” Shiro commanded, picking up his pace.

Keith obeyed, his feet up around his ears, his fingers locked in a death grip around his ankles. He was impossibly full, his ass stuffed with the toy, and his front pummeled by Shiro’s thick cock. 

It was pure bliss.

A drop of sweat dripped from Shiro’s brow, his eyes hard as he continued his assault. Shiro slapped Keith’s ass, rising up, his hands gripping the back of Keith’s thighs.

“So good. Feel so good.”

Shiro was lost, his entire body electric as it merged with Keith’s. He swung his hips faster, driving into Keith with enough force to push the omega up the mattress. Keith dropped his ankles, instead reaching up to brace against the wall as Shiro plunged into him over and over again.

Keith began to tighten around him, and Shiro exploded, his orgasm blindsiding him, hips stuttering as his hot cum filled the squirming omega beneath him. 

“Fuck,” Shiro moaned, and he reached between them, gripping the base of the dildo and fucking Keith with it as his knot swelled, sealing them together.

Keith threw his head back, his cries echoing around the room, his entire body drawn tight. 

“That’s it, baby. Let me see you come.”

Just as Keith’s body began to quiver, his untouched cock surging, Shiro ripped the dildo from his as, and Keith screamed, his body convulsing as he came. 

“Kashi!” Thick ropes of sticky seed striped Keith’s chest, tears leaking from his scrunched eyes.

“I’ve got you,” Shiro murmured, leaning down to kiss Keith’s cheeks, his tongue swiping up to lick away the tears. 

He kissed Keith’s jaw, his neck, his teeth finding the marks at Keith’s throat and biting down hard enough to renew the mate marks there. 

Shiro gathered Keith in his arms and rolled so that Keith was resting on top of him. 

“Thank you,” Keith whispered, rubbing his nose across Shiro’s chest. 

“Thank _you_ ,” Shiro replied, tilting his head to expose his throat in a silent request.

Keith moved in, the knot pulling a bit as he shifted from side to side, biting the marks on Shiro’s neck.

“I can’t believe we get a whole week of this,” Keith said, voice drowsy, eyes closed. 

“I know. If we keep it up, you just might kill me.”

“Have fun explaining that absence to the captain,” Keith countered.

Shiro snorted a laugh. “If I’m dead, you’re the one who has to do the explaining.”

“Hmmm. Guess you’ll just have to learn to keep up.”

Shiro’s scent rose around them at the challenge, his inner alpha excited by the prospect of pleasuring his omega. His mate.

“Don’t threaten me with a good time.”

“It’s not a threat,” Keith said, shuddering as Shiro’s knot released. “It’s a promise.”  
  


**Author's Note:**

> The next time they fuck, Keith is on top and in charge and makes Shiro fall apart...
> 
> Thank you for reading! More thirsty fandom nonsense on my Twitter: [@nihilistshiro](https://twitter.com/NihilistShiro)


End file.
